1. Field of the Invention
The present invention relates to a digital camera or the like, more particularly to a movement controller for moving a zoom lens and a focus lens to a designated position at a high speed, a camera apparatus, a movement control method, and a movement control program.
2. Description of the Related Art
For the past number of years, it has often been the case that when a zoom lens or a focus lens is moved to a designated position at a high speed for camera focus adjustment or the like, DC motors are used for cost saving and downsizing instead of stepping motors. Differently from the case of processing to stop the stepping motor, when the DC motor is stopped, it is necessary to consider free running due to inertia and start stop processing when a lens is located before a desired stop position. That is, in the case that the brake is suddenly applied when the lens is moved at a high speed without previous deceleration as shown in FIG. 10A, fluctuations are caused in the stop position according to the brake effect.
For example, as shown in FIG. 10B, a technique is disclosed in which a DC motor is decelerated to a given speed when the lens approaches a first distance (deceleration start position X) in relation to a stop target position O, under this condition, such a given speed is maintained until the lens approaches a second distance (complete stop processing start position) and the brake is applied when the lens approaches the second distance to completely stop the lens (refer to Japanese Laid-Open Patent Publication Nos. H05-257060 and 2004-317997).
According to the foregoing related art, since the brake is applied after deceleration to the given speed, free running distance becomes short, and precision of the stop position can be improved. In addition, since the lens is moved at the maximum speed until deceleration to the given speed, the lens can be moved at a high speed and precisely to the designated position.
However, in the foregoing related art, how to set the given speed decelerated before the stop target position is to be set is problematic. That is, when the given speed is set high, some free running is generated even after the brake is applied. Since such a free running distance is changed according to the DC motor, fluctuations depending on each peripheral component, ambient temperatures and the like, sufficient precision is not able to be obtained. Meanwhile, when the given speed is set low, the precision becomes favorable. However, elapsed time until the lens reaches the stop target position becomes long, and therefore high speed operation is not able to be expected. Further, since acceleration is significantly changed due to deceleration, deceleration is not able to be made smoothly, and vibration and noise in deceleration become large.